Automated Laser-Treatment System With Real Time Integrated 3D Vision System for Laser Debridement and the Like

ABSTRACT

A method for automated treatment of an area of skin of a patient with laser energy. The method including: identifying the area to be treated with the laser; modeling the identified area of the skin to be treated; and controlling the laser to direct laser energy to within the modeled area of the skin.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. Ser. No.11/888,813 filed on Aug. 2, 2007 which claims priority to U.S.provisional patent application Ser. No. 60/835,024, filed on Aug. 2,2006, the entire contents of each of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to automated control of a laserhead for treatments on human skin, and more particularly to automatedcontrol of a laser head for laser debridement of burns.

2. Prior Art

Thermal burns and vesicating (blistering) due to chemical warfare agentssuch as sulfur mustard and Lewisite induced skin injuries can vary inseverity between second degree and third degree. Vesicant injuries inparticular can take several months to heal, necessitating lengthyhospitalizations, and result in significant cosmetic and/or functionaldeficits.

The initial step in the repair of a thermal or chemical burn wound is toremove the dead skin, called wound debridement, and replaces it with aviable biological dressing. Autologous skin from another site of thepatient, in the form of a split thickness skin graft is the method ofrepair that is most often employed. In special circumstances a flap ofmuscle with its attached blood supply may be used to cover severelyburned areas that lack sufficient blood supply to allow the splitthickness graft to become engrafted.

It has been shown that early excision at less than one week after theburn significantly reduces blood loss. Later excisions after 7-10 daysare associated with significantly greater blood loss. The reason forthis is that the very presence of the dead skin causes an inflammatoryreaction which results in a significant increase in blood flow to theskin. Consequently, when burned skin is excised from the body after 7-10days there is a much greater blood loss. Others have analyzed thesurvival rates after burns over a 50 year period and concluded thatprompt excision of the eschar after the burn occurred was largelyresponsible for reducing the mortality after burns, and resulted in asignificant improvement of survival rate.

It is, therefore, apparent that early excision of the burn and immediatecoverage of the wound with a biologic dressing, preferably autologousskin, if it is available, is the optimal method for caring for thethermal and chemical burn wound.

There are various methods of wound debridement. The method of wounddebridement that is most commonly used is surgical excision usingstainless steel cutting blades, which can be mounted on different typesof handles and into which are built methods of controlling the depth ofthe excision. The excision may be superficial, as in a deep dermal burn,by cutting off the injured tissue through the appropriate level of thedermis; or in the case of a full thickness burn, the entire skin: i.e.,epidermis and dermis may be cut off either leaving the subcutaneoustissue or the fascia exposed. This method of using a steel blade as acutting instrument works well in the hands of a well trained surgeon.However this method is time consuming in large burns and is oftenassociated with the loss of considerable amounts of blood. The leastamount of blood is lost when the entire thickness of skin andsubcutaneous tissue must be excised. The reason for this, is that inthis setting the individual blood vessels arising from the deepertissues can be identified and can be ligated before they enter the skin.Whereas excisions through either superficial or deeper dermis areassociated with significantly more bleeding, since the distinct nutrientvessels which arise from the deeper tissues have arborized into numerousbranches as they progress towards the surface of the skin.

Until recently, the standard method for burn debridement, as statedearlier has been the use of stainless steel blades. Recent advances havebeen made in improving the healing of thermal and chemical burns using avariety of techniques to debride damaged tissue, including the use ofmedical lasers. One promising modality for excision (debridement) uses alaser beam. Excision using a laser beam would be associated withsignificantly reduced morbidity, since the amount of blood lost when alaser beam is used has been shown to be significantly reduced. It isimportant to note also that the percentage of successful wound closuresafter the excision using grafts is the same irrespective of whether alaser or a steel knife was used to remove the eschar. Laser vaporizationof full thickness burn eschar in a porcine model with immediateengraftment was shown to be associated with minimal blood loss and equalgraft take.

Current uses of lasers in dermatological practice as well as the typesof lasers used for each specific procedure are well known. They includeCO₂ and Er:YAG lasers as being the most appropriate for cutaneousresurfacing.

The CO₂ laser emits radiation at a wavelength of 10,600 nm. The fluenceshould exceed the vaporization threshold of skin (5 J/cm²)^(4,5) and thepulse duration (or its scanning laser equivalent, the ‘dwell time’)should be shorter than the τ(695-950 ms) although pulse widths of up to1 ms appear to be acceptable in vivo. At lower fluences there is moredesiccation and carbonization and a higher likelihood of scarring. Thedepth of vaporization and thermal necrosis depend on the fluence, dwelltime and number of passes. Two different laser systems are in commonuse. High energy pulsed lasers produce wide diameter pulses with beamdiameters of up to 3 mm. A computerized pattern generator can be used inthe treatment of relatively large areas. With low energy scanned focusedbeams, a computer-controlled mirror rapidly scans a focused beam acrossa predetermined area. The dwell time is 300-900 ms depending on thedepth of damage required. Clinical outcomes using these two differenttypes of system can only be compared if the fluences and number ofpasses are considered.

The Er:YAG (erbium:yttrium-aluminium-garnet) lasers produce radiation(λ=2940 nm) with a higher absorption coefficient for water than the CO₂laser and a lower optical penetration depth (1 μm and 20 μm,respectively). Because ablation is inversely proportional to the opticalpenetration depth, Er:YAG lasers require a lower fluence for tissueablation. This is a largely photoaccoustic rather than a photothermalreaction. The depth of vaporization is 2-4 μm for each 1 J/cm² fluenceand very superficial peels may be achieved. Epidermal lesions can beablated accurately, but deeper peels may be limited by intraoperativebleeding due to the relatively thin layer of residual thermal damage.Attempts to improve haemostasis have been made by adapting the Er:YAGlaser to produce longer pulses and/or lower fluences or throughcombination with low-fluence CO₂ or with secondary Er:YAG lasers.Side-by-side comparisons suggest that for the same depth of injury,re-epithelialization time and persistence of erythema is shorter insites treated with the Er:YAG as opposed to the CO₂ laser. However, thethickness of subsequent fibrosis or ‘collagen remodeling’ is greater inCO₂ laser-treated sites, possibly reflecting greater underlying thermaldamage.

Er:YAG lasers have been used for a wide variety of procedures, rangingfrom facial resurfacing to burn debridement. They have been shown to beparticularly useful in the debridement of partial-thickness thermalburns and in the management of deep Lewisite injuries. A review of theliterature clearly indicates that laser debridement produced equallygood results with excisions performed with a steel blade. In addition,unlike the Gaussian beam profiles created by CO₂ lasers, Er:YAG laserbeams tend to be uniform and produce uniform depths of ablation. Thus,it can be concluded that the use of erbium:yttrium-aluminum garnet(Er:YAG) laser in the skin resurfacing to debridement of deep partialthickness burns, including those caused by sulfur mustard havedemonstrated benefits of this method of excision.

It is noted that debridement with Er-YAG and CO₂ lasers promise toprovide great benefits in the treatment of leg ulcers (e.g., venousstasis ulcers, pressure ulcers, diabetic foot ulcers). Additionally, legulcers (e.g., venous stasis ulcers, pressure ulcers, diabetic footulcers) and penetrating injuries to the skin can require frequentdebridement to help these wounds to heal.

Lasers have a wide range of applications in dermatology. Such proceduresinclude removal of hair, tattoos, freckles, wrinkles, acne, sun-damagedskin, scars-including surgical and acne scarring, facial red veins andother vascular lesions, skin resurfacing and malformations (such as portwine stains) and hair and tattoo removal. Lasers are also being used orinvestigated for removal of keloids and hypertrophic scars as well asviral warts, seborrhoeic keratoses, skin cancers, and psoriasis plaques.

One major drawback of all currently available laser systems is that theyrequire the physician and/or surgeon to move a hand piece over thedamaged area, which is very time-consuming given an injury with a largesurface area. The process also requires a skilled physician/surgeon, anda steady hand. The design of small hand held scanners on the ends ofarticulated arms has weakened this drawback to a limited extent.However, the scanned areas are relatively small and thephysician/surgeon still needs to move the scanner head over relativelylarge treatment areas. A time savings could be realized with a systemthat could scan very large areas of a patient's body and perform preciselaser treatment, such as debridement automatically and quickly withminimal physician/surgeon/technician involvement. In fact, certain lasertreatment processes are so slow that they are effectively impracticalfor treating patients. This is the case, for example, for erbium:YAGlasers used for laser debridement of chemical and thermal burn injuries.For the latter applications, such a system would greatly decreasemedical logistical burden, especially in a mass casualty scenario.

In the present disclosure, the various embodiments of the presentinvention are described in terms of their application for laserdebridement of chemical or thermal burns. However, it is appreciated bythose familiar with the art that the described embodiments can also beused as automated systems for a number of other skin treatments such asfor removal of hair, tattoo, freckle, wrinkle, acne, sun-damaged skin,acne scarring facial red veins and other vascular lesions andmalformations (such as port wine stains) with minimal effort. Suchlasers treatments have also shown great promise for removal of keloidsand hypertrophic scars as well as viral warts, seborrhoeic keratoses,skin cancers and psoriasis plaques.

It is also appreciated by those skilled in the art that the describedembodiments of the present invention are modular in design so that eachcomponent of the system and its operating software could be readilyupdated and upgraded.

SUMMARY OF THE INVENTION

A need therefore exists for automated laser treatment systems thatrequire minimal physician/surgeon/technician interaction during thetreatment and after the physician/surgeon/technician or appropriatemedical personnel has indicated the treatment area(s) and set theoperating parameters of the system.

There is also a need for automated and precision laser treatment systemsto achieve precision and speedy treatment of patients, particularly whenlarge areas have to be treated. Such a precision and automated systemwould allow a significant amount of time saving to be achieved with asystem that could scan very large areas of a patient's body and performprecise debridement automatically and quickly with minimalphysician/surgeon involvement.

There is also a need for automated laser debridement systems for thetreatment of chemical and thermal burn injuries to significantly reducemedical logistical burden, especially in a mass casualty scenario.

There is also a need for automated and precision laser treatment systemsthat could be operated by medical personnel under the supervision of aremotely located specialized surgeon, especially in a mass chemical burncasualty scenario.

Accordingly, a novel method is provided that could be used to developautomated laser treatment systems for the treatment of wide varieties ofskin and other ailments of exposed body surfaces, such as theaforementioned chemical and thermal burn debridement and otherdermatological conditions that are treatable with laser or other lightsources.

The present automated laser treatment systems and methods for cutaneousconditions and injuries and other similar laser treatment applicationscomprises one or more of the following components:

-   -   1. A multi-purpose near real-time 3D vision system for scanning        the indicated area(s) on the surface of the patient body. The        vision system is used for 3D measurement of the indicated        area(s) on the surface of the patient body and development of a        3D map of the said area(s); to track the actual position of the        laser head at all times, particularly during the laser        treatment; to continuously and in real-time update the 3D map of        the indicated area(s) in case of the patient movement or        geometrical variations in the surface area(s); to continuously        and in real-time update the 3D map of the indicated area(s) and        its location relative to the laser head (robot end-effector when        a robot is used to position the laser head), in case of the        patient movement and geometrical variation in the treatment        surfaces or unwanted movement of the laser head, for example due        to an accidental running into its support structure; to        continuously and in real-time monitor the actual position of the        treating laser spot(s) over the indicated treatment area(s) and        comparing it with the planned positioning of the said treating        laser spot(s) and calculating the positioning error of the said        treating laser spot(s) and providing it to the system controller        to affect corrective action or if the error is beyond a selected        threshold, to shut down the treatment process for safe operation        of the system; and to provide and update the map of treated        surfaces and the number of passes and the corresponding system        parameters set by the physician/surgeon or the medical personnel        and automatically by the system as a record of patient        treatment. For this purpose, a number of vision systems are        currently available and could be used. For example, one may use        the real-time 3D surface shape measurement system based on a        digital fringe projection and phase-shifting technique as        described in the U.S. Pat. Nos. 6,788,210 and 6,438,272 can be        used.    -   2. The system may be designed in the following two basic system        configurations using either a robotic arm to provide the means        to scan the treatment surface (with or without a pattern        scanning laser heads), or using a programmable large-area laser        scanning system:        -   a. Embodiment with a robotic arm: In this embodiment, the            Er:YAG laser head is attached to the terminal link of the            robot manipulator and constitutes its end-effector. In            general, the robot can have a minimum of 5 degree-of-freedom            to be capable of positioning and orienting the laser beam            over the treatment area of arbitrary topology. However, for            the treatment of more uniform and relatively smaller            surfaces, robotic arms with fewer degrees-of-freedom may be            used. The robot arm must also be dexterous enough within its            intended workspace to cover the maximum treatment surface            without patient and/or machine movement.        -   b. Embodiment with a programmable, large-area laser scanning            system.    -   3. A system for removing smoke and fumes generated during the        treatment and filtering and collecting the generated residue for        disposal.    -   4. A computer based central control unit with touch-screen        monitor or the like. The system would preferably allow the        physician to interactively circumscribe the treatment areas on        the monitor screen, and enters operating parameters of the        laser. The physician may, for example, subdivide the treatment        areas for different treatment parameters and even lasers and        number of passes.    -   5. A computer vision system that can automatically determine the        treatment area, such as the burned area, scarred area, tattoo,        etc. and control the laser head accordingly.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the apparatus andmethods of the present invention will become better understood withregard to the following description, appended claims, and accompanyingdrawings where:

FIG. 1 illustrates a schematic of an embodiment of an automated lasertreatment system.

FIG. 2 illustrates a close up view of the treatment area and the maincomponents of the system of FIG. 1.

FIG. 3 illustrates a schematic of another embodiment of an automatedlaser treatment system.

FIG. 4 illustrates a close up view of the treatment area and the maincomponents of the system of FIG. 3.

FIG. 5 illustrates a schematic of yet another embodiment of an automatedlaser treatment system.

FIG. 6 illustrates a close up view of the treatment area and the maincomponents of the system of FIG. 5.

FIG. 7 illustrates a schematic of still yet another embodiment of anautomated laser treatment system.

FIG. 8 shows the system of FIG. 7 positioned for treatment of a patient.

FIGS. 9 and 10 illustrate the treatment head of the system of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The characteristics of disclosed embodiments of the present automated(Er-YAG or other) laser debridement and for cutaneous injuries are asfollows:

-   -   a. The physician or medical technician will identify the general        areas within which the treatment areas are positioned using a        simple marker. Alternatively, a computer vision system will        identify the burned tissue due to differences between the burned        tissue and healthy tissue that are recognizable by the vision        system. An appropriate vision system, such as the aforementioned        high resolution and near real-time 3D surface mapping vision        system, generates a 3D map of the circumscribed areas,        preferably together with their color and texture, and displays        the generated images on a touch-screen monitor. Two or more tick        marks along the circumscribing curves can be used for more        accurate and faster calculation of the relative positioning of        the 3D surfaces relative a fixed reference system. This        reference system can be fixed to the 3D surface mapping vision        system to minimize measurement errors. It is, however,        appreciated by those familiar with the art that instead of the        aforementioned tick marks, other marks, the circumscribing        curves, landmarks on the treatment surface, or any other        commonly used recognition algorithms and/or their combinations        may also be used.    -   b. The physician circumscribes the treatment areas on the        touch-screen monitor and enters the operating parameters of the        laser, including the number of passes over each region of the        treatment areas.    -   c. The system is capable of generating 3D maps of very large and        multiple treatment areas over the patient's body using the        aforementioned high-resolution and real-time 3D surface mapping        vision system.    -   d. The curve(s) circumscribing the general area(s) are used as        landmarks (preferably with two or more tick marks on the curves        or markers) to update the 3D maps of the treatment areas, and        provide continuous sensory information indicating the position        of the laser beam (and laser head and/or the robot arm with the        embodiments using robot arms) relative to the treatment areas.        This sensory information is used to close the feedback loop on        the laser beam travel along its planned trajectory over the        treatment area.    -   e. The high-resolution and fast 3D surface mapping vision is        used to continuously update the maps of the treatment areas to        account for changes in their geometry as a result of patient        movement or muscle actions, using the provided landmarks (the        circumscribing curves, tick marks, markers, etc. used). In the        embodiments using robot arms, the position of the laser head and        the robot arm (preferably the terminal link to which the laser        head is usually attached) is also updated continuously,        preferably using three or more marked points on the laser head        and the robot arm.    -   f. For the embodiments that use robot arms, for additional        safety and fine adjustments, matching calibration images may        also be projected over the treatment area by the projector of        the 3D surface mapping vision system and by image projectors        mounted on the laser head. The vision system would then monitor        the two images and determines the amount of adjustment in the        position of the laser beam and robotic arm that is needed to        overlay the two projected images. The system controller uses        this information and the corresponding error information to        close its feedback loop.    -   g. The actual position of the laser beam on the body surface is        also monitored continuously by the 3D surface mapping vision        system. Thereby providing at least one independent means of        automatically monitoring its correct positioning and path of        scanning in real time. This will be in addition to the health        professional operating the proposed (e.g., Er-YAG laser        debridement) system. In one embodiment, a second vision system        is provided in addition to the aforementioned 3D surface mapping        system with the primary purpose of continuously monitoring the        position of the laser beam on the treatment area and comparing        it with the desired position of the beam and directly providing        a signal to the system controller to shut off the power to the        treatment laser when an specified error threshold has been        reached.    -   h. The disclosed automated system can scan large areas of the        body that are in need of treatment such as wound debridement        following a skin injury and perform the debridement with minimal        surgeon involvement. For chemical and thermal burn debridement,        the system preferably uses erbium:yttrium-aluminum-garnet        (Er:YAG) laser and allows the attending physician to program the        instrument to treat, such as debride specific areas of damaged        tissue. Physicians will be able to interactively circumscribe        the treatment areas on a video screen and enter operating        parameters of the laser. The system will then quickly and        automatically perform the debridement.

The disclosed embodiments of the “automated (e.g., Er-YAG or CO₂) laserdebridement system” for cutaneous injuries, hereinafter referred to asALDS, or for the laser treatment of other aforementioned conditions,hereinafter referred to as “automated laser treatment systems”, ALTS,consist of the following three major hardware components:

-   -   1. A (preferably 3D) vision or other similar system for        treatment surface measurements and/or recognition;    -   2. A laser source(s), e.g., an Er-YAG or CO₂ laser source alone        in combination with one or more other laser sources;    -   3. Either a robotic arm or at least one wide-area scanning laser        head.

The vision or other similar system for treatment surface measurementscan be a 3D vision system, and can provide a high-resolution, fast, andnear real-time 3D surface shape measurement and mapping, includingmapping of curves and lines and points on the measured surfaces. Onesuch system using a digital fringe projection and phase-shiftingtechnique is described in the U.S. Pat. Nos. 6,788,210 and 6,438,272. Ashort description of this system together with its specific use for thevarious embodiments of the present invention is provided below. It isnoted that as previously indicated, the description is provided by itsapplication to Er:YAG lasers used for debridement, but the descriptionis general and applicable to any one or combinations of lasers used forany treatment of exposed surfaces of the body.

The vision or other similar system can be multi-purpose, i.e., it willbe used to: 1) scan the indicated area(s) for debridement; 2) develop a3D map of the said surfaces, curves circumscribing the treatment areas,and the markings such as tick marks used for positioning indications; 3)track the Er:YAG laser head (when robots are used to move laser head) ortrack laser beams (when a scanning laser head is used alone) during thedebridement; 4) continuously update the 3D map of the surfaces beingtreated to correct for changes in the 3D geometry of the surfaces due tomuscle action, body movement, etc.; 5) when robots are used to movelaser head, to continuously update the spatial position of the robotend-effector, i.e., the Er-YAG laser head, relative to the treatmentsurfaces; and 6) thereby provide the means to close the feed-back loopfor the Er-YAG laser scanning process of the indicated treatment areas.The vision system may also be used to recognize the areas to be treated,such as recognizing burned tissue as opposed to healthy tissue,recognizing scarred tissue, recognizing a tattoo to be removed,recognizing a port-stain, etc.

The operating system may also be used to continuously update the 3D mapof the treatment areas with information regarding the treated regionsand the number of passes in each region. The information may be storedin the patient file for future use.

The vision based system can be a high-resolution, real-time, 3D surfacemeasurement system, which operates based on a digital fringe projectionand phase-shifting technique. It utilizes a single-chip DLP projector toproject computer generated fringe patterns onto the object and ahigh-speed CCD camera, which is synchronized with the projector toacquire the fringe images at a frame rate of 120 frames per second(fps). Based on a three-step phase-shifting technique, each frame of the3D shape is reconstructed using three consecutive fringe images.Therefore the 3D data acquisition speed of the system is 40 fps.Together with the fast three-step phase-shifting algorithm and parallelprocessing software being used, the system provides high-resolution,real-time, 3D shape measurement at a frame rate of up to 40 fps and aresolution of 532×500 points per frame.

In addition, a color CCD camera can also be used to capture images fortexture mapping over the aforementioned mapped surfaces. Theavailability of this feature in the vision system provides the means forfurther enhancement of the system to continuously monitor the effects ofthe Er-YAG laser scanning during the treatment and at certain periods oftime post treatment.

Among all existing vision based surface mapping techniques, stereovisionis probably the most studied and used method. Traditional stereovisionmethods estimate shape by establishing spatial correspondence of pixelsin a pair of stereo images. A new concept called spacetime stereo hasbeen developed, which extends the matching of stereo images into thetime domain. By using both spatial and temporal appearance variations,it was shown that matching ambiguity could be reduced and accuracy couldbe increased. The shortcoming of spacetime stereo or any other stereovision method is that matching of stereo images is time-consuming,therefore making it difficult to reconstruct high-resolution 3D shapesfrom stereo images in real time.

Another major group of vision based surface mapping techniques usesstructured light, which includes various coding methods and employsvarying number of coded patterns. Unlike stereo vision methods,structured light methods usually use processing algorithms that are muchsimpler. Therefore, it becomes possible to achieve real-timeperformance, i.e., measurement and reconstruction. For real-time shapemeasurement, there are basically two approaches. The first approach isto use a single pattern, typically a color pattern. The use of thisapproach employs a color-encoded Moire technique for high-speed 3Dsurface contour retrieval. Others have developed a rainbow 3D camera forhigh-speed 3D vision. Still others have developed a color structuredlight technique for high-speed scans of moving objects. Since the abovemethods use color to code the patterns, the shape measurement result isaffected to varying degrees by the variations of the object surfacecolor. In general, better accuracy is obtained by using more patterns.Thus, the above methods sacrifice accuracy for improved measurementspeeds.

Another structured light approach for real-time shape measurement is theuse of multiple coded patterns with rapid switching between them so thatthey could be captured in a short period of time. This approach has beenused and develops a real-time 3D model measurement system that uses fourpatterns coded with stripe boundary codes. The acquisition speedachieved used was 15 fps, which is good enough for scanning slowlymoving objects. However, like any other binary-coding method, thespatial resolution of these methods is relatively low because the stripewidth must be larger than one pixel. Moreover, switching the patterns byrepeatedly loading patterns to the projector limits the switching speedof the patterns and therefore the speed of shape measurement.

An example of a system for use with the present application is disclosedin U.S. Pat. Nos. 6,788,210 and 6,438,272 which provide a vision systemfor real-time and high-speed 3D shape measurement, with full capabilityof providing fast updating of the 3D surface maps and maps of the curvesindicating the treatment areas and positioning markings such as tickmarks of the said curves, thereby serving as the sensor to close thepresent automated debridement systems control loop and as the means toprovide for safe operation of the system, by for example, shutting thetreatment laser beam off when the error between the actual position anddesired position of the treatment laser beam is more than a selected(programmed) threshold. This method is based on a rapid phase-shiftingtechnique. This technique uses three phase-shifted, sinusoidal grayscalefringe patterns to provide pixel-level resolution. The patterns areprojected to the object with a switching speed of 240 fps. This systemtakes full advantage of the single-chip DLP technology for rapidswitching of three coded fringe patterns. A color fringe pattern withits red, green, and blue channels coded with three different patterns iscreated by a PC. When this pattern is sent to a single-chip DLPprojector, the projector projects the three color channels in sequencerepeatedly and rapidly. To eliminate the effect of color, color filterson the color wheel of the projector are removed. As a result, theprojected fringe patterns are all in grayscale. A properly synchronizedhigh-speed B/W CCD camera is used to capture the images of each colorchannel from which 3D information of the object surface is retrieved. Acolor CCD camera, which is synchronized with the projector and alignedwith the B/W camera, is also used to take 2D color pictures of theobject at a frame rate of 26.7 fps for texture mapping. Together withthe fast 3D reconstruction algorithm and parallel processing software,high-resolution, real-time 3D shape measurement is realized at a framerate of up to 40 fps and a resolution of 532×500 points per frame. Othersystems for 3D shape measurement known in the art can also be used inthe system and methods of the present invention, such as thosecommercially available from Blue Hill Optical Technologies, located inNorwood, Mass. or Nutfield Technology, Windham, N.H.

For the projection of the computer-generated patterns, a single-chip DLPprojector is used, which produces images based on a digital lightswitching technique. With this system, a complex facial surface has beenmapped at 40 fps (the accuracy of the system being 0.1×0.1×0.1 mm),providing an excellent speed and resolution for the present automatedlaser debridement and treatment systems and the like.

The color image is produced by projecting the red, green, and bluechannels sequentially and repeatedly at a high speed. The three colorchannels are then integrated into a full color image. To take advantageof this projection mechanism of a single-chip DLP projector, a colorpattern which is a combination of three patterns in the red, green, andblue channels is created. The projector has no color filters for amonochrome mode of operation. As a result, when the color pattern issent to the projector, it is projected as three grayscale patterns,switching rapidly from channel to channel at 240 fps. A high-speed B/Wcamera, which is synchronized with the projector, is used to capture thethree patterns rapidly for real-time 3D shape measurement. An additionalcolor camera is used to capture images for texture mapping. To obtain 3Dmaps and color information simultaneously, multi-threading programmingis used to guarantee that two cameras work independently and that thetiming of image grabbing is only determined by the external triggersignal.

For more realistic rendering of the object surface, a color texturemapping method is used that is based on a sinusoidal phase-shiftingmethod. In this method, the three fringe patterns have a phase shift of2π/3 between neighboring patterns. Since averaging the three fringepatterns washes out the fringes, a color image can be obtained withoutfringes by setting the exposure time of the color camera to oneprojection cycle or 12.5 ms.

The above system provides the capability of rapidly projecting andcapturing three coded patterns rapidly. The employed fast three-stepphase-shifting method provides a real-time 3D reconstruction speed andhigh measurement accuracy of the order of 0.1×0.1×0.1 mm. The sinusoidalphase-shifting method that has been used extensively in opticalmetrology to measure 3D shapes of objects at various scales. In thismethod, a series of phase-shifted sinusoidal fringe patterns arerecorded, from which the phase information at every pixel is obtained.This phase information helps determine the correspondence between theimage field and the projection field. Once this correspondence isdetermined, the 3D coordinate information of the object can be retrievedbased on triangulation. A number of different sinusoidal phase-shiftingalgorithms are available. In the present system, a three-stepphase-shifting algorithm similar to the traditional three-step algorithmis used, which requires three phase-shifted images.

In one embodiment, the automated Er-YAG laser debridement system uses acommercially available Er-YAG laser head and related system (such as theProfile Surgical Laser system from Sciton, Inc., Palo Alto, Calif.). Inthis system, the laser head is attached directly to the end-effector(e.g., the last free link) of a robot manipulator arm. Theaforementioned 3D vision system camera and projector head is fixed tothe patient bed structure. The patient is considered to be positioned onthe bed in the appropriate posture to expose the treatment area to thevision system. In this system configuration, the vision system cameraand projector unit is attached at a far enough distance from thetreatment surface to allow a relatively large field of view to scan thepatient body surface somewhat beyond the circumscribed treatment area(s)to allow for certain amount of body movement during the treatment.

It is noted that all available Er-YAG or other laser heads that arecurrently available are designed to be operated manually. For thisreason, to allow the user to have more control as to the positioning ofthe laser head and thereby the laser spot over the treatment surfacearea, the laser heads are optically designed to be held a relativelyshort distance (mostly around 10-15 cm) from the treatment area. Forthis reason, the vision system camera and projector unit has to bepositioned further away from the laser head and the treatment area toallow a large enough filed of view. As a result, the laser head and the3D vision system camera and projector unit cannot be easily co-locatedat the end-effector of the robot.

Obviously in certain dermatology applications in which the treatmentarea is relatively small and can be captured well from a shorter 10-15cm distance, then the 3D vision system camera and projector unit and thelaser head component can be attached directly to the end-effector of therobot manipulator. Such a configuration is always preferred since therelative position of the vision system and the laser head is fixed andcalibration and real-time control of this relative position does nothave to be made before and during the treatment process.

The schematic of this automated Er-YAG laser debridement system designconfiguration 100 is shown in FIG. 1. A close up of the treatment areaand the main components of the system is shown in FIG. 2. The 3D visionsystem 101 is shown to be attached to an adjustable stand 102 that ispositioned in the proper view of the treatment area 103 of the subject104. The treatment area 103 is clearly shown in FIG. 2 with its markedcircumscribing curve 105 and several tick marks 106 to increase surfacemodel position and orientation measurement accuracy. Additional markerssuch as the three small target markers 107 such as those shown in theclose-up of FIG. 2 may be added to increase the vision systemcalibration distances. The three circles 107 above the treatment areaare preferably projected by lights (not shown) fixed to the laser head108, which is fixed to the end-effector 110 of the robot arm 109 and areused as secondary means to continuously calibrate the position of thelaser head 108 (i.e., the robot arm 109) in the coordinate system of the3D vision system 101.

A smoke evacuation vacuum head 111 is provided to evacuate the generatedsmoke and debris resulting from the debridement or other operations.Such smoke evacuation systems are well known in the art and may use aircirculation to increase the efficiency of the evacuation system. Theevacuated flow is usually filtered using appropriate filtering systemsthat are routinely cleaned and their filters replaced when suchdisposable filters are utilized.

This embodiment has the following configuration, characteristics,advantages and shortcomings relative to other embodiments describedbelow:

-   -   1. A pattern scanning and currently available Er-YAG laser head        108 is preferably used. The use of pattern scanning laser heads        would significantly reduce the demand on the robot arm 109 speed        and precision. This is the case since the robot arm 109 need        only position the laser head 108 at discrete positions over the        treatment area 103 and allows the pattern scanning head to scan        discrete areas, preferably slightly overlapping areas, to        eventually cover the entire treatment area 103. That is, the        robot arm 109 needs only to make the so-called point-to-point        motions and is not required to perform the actual movement of        the laser beam 112 over the treatment areas. One other advantage        of using the said pattern scanning laser heads is that the robot        arm 109 may be locked at each said positioning of the robot arm,        thereby minimizing the effects of someone or some object bumping        into the robot arm 109. One shortcoming of the use of currently        available pattern scanning laser heads is that nearly all such        devices provide only a limited choice on the available        geometrical shape of the area that can be scanned, and it is        therefore almost always impossible to fully cover treatment        areas with complex geometries, particularly in areas that are        not mostly flat and contain curved surfaces.    -   2. The aforementioned 3D vision system camera and projector unit        101 is preferably attached to an adjustable and locking vision        system stand 102 as shown in FIGS. 1 and 2, and is positioned in        a proper position prior to the start of treatment process to        provide it with a good view of the treatment area 103. Proper        positioning can be greatly facilitated by providing a projected        target area onto the treatment surface area (not shown) similar        to X-ray machines during this adjustment process. It is noted        that in the schematics of FIG. 1 the adjustable vision system        stand 102 is shown to be attached to the treatment bed 113 with        an attachment structure 114. Alternatively, the adjustable        vision system stand 102 may be a separate unit (not shown),        preferably on locking wheels, that is positioned in an        appropriate location by the medical personnel prior to        treatment. The latter option is preferred when the treatment bed        113 is not dedicated solely for use with the present laser        treatment system 100 and is used for other types of treatments        as well.    -   3. At certain positions, the laser head 108 and/or the robot arm        109 may temporarily block the field of view of the 3D vision        system 101. The blockage of the view, unless it blocks a        significant portion of the treatment area 103 and the surface        markers 104, 105 and 107, should not interfere with the proper        operation of the system since from such partial views (and the        view of the laser head markers not shown) the 3D vision system        101 can determine the actual positioning of the laser spot over        the blocked treatment area surfaces. To increase the level of        safety even further, for relatively prolonged blockage of the        areas being treated, the present system could be programmed to        periodically stop the laser debridement process, move the laser        head 108 away to expose the entire treatment area 103 and the        surface markers 104, 105 and 107, update the treatment area        surface model, and then resume the laser debridement process.    -   4. Since the position of the laser head 108 is not fixed        relative to the 3D vision system camera and projector unit 101,        before and on a regular time intervals during the laser        debridement process, the position of the laser head 108 and the        robot manipulator arm 109 relative to the 3D vision system 101        has to be determined as previously described and the information        updated (adjusted) to eliminate any potential error        accumulation.    -   5. Since the distance from the laser head 108 to the treatment        surface 103 is relatively small, the laser head 108 can only        scan a relatively small surface area with the indicated pattern.        This means that the robot manipulator arm 109 must make a        significant number of moves to cover a relatively large area.    -   6. Since the distance from the laser head 108 to the treatment        surface 103 is relatively short, there is less chance of        accidental reflections and/or running into the beam path by the        medical personnel and the patient.    -   7. This system configuration would tolerate a relatively large        movement of the patient 104 during the treatment.    -   8. The robot manipulator requires at least five        degrees-of-freedom to allow the laser head 108 to be positioned        anywhere over the indicated treatment area surfaces 103 and        oriented perpendicular to the treatment surface within an        appropriate range of approach angle. In most cases, an approach        angle of around ±15 degrees or even larger would be acceptable        since the resulting laser spot distortion and power density over        the laser spot would be minimal. The scanning pattern generation        capability of the laser head 108 is considered to be capable of        handling any angular positioning of the laser head 108 about the        laser beam 112 axis. Otherwise a sixth degree-of-freedom has to        be added to the robot manipulator arm 109 to allow for        independent rotation of the laser head 108 about the general        laser beam 112 axis to arbitrarily position the scanning pattern        area over the treatment surface area 103. In many situations,        however, particularly when relatively small and flat surfaces        are being treated and since slight laser beam 112 deviation from        the direction perpendicular to the treatment area is well        tolerated due to the resulting small deviations from the        designated laser spot and resulting power density, then as few        as 3 degrees-of-freedom for robot arm 109 may be sufficient for        positioning of the laser head 108 at discrete positions over the        treatment area 103.

Another embodiment of the present invention is shown in the schematicsof FIG. 3, a close-up of which is shown in FIG. 4. This embodiment ofthe automated Er-YAG laser debridement system 120 has a configurationthat is similar to that of the previous embodiment, except in thepositioning of the 3D vision system camera and projector unit 121. Inthis system configuration, the 3D vision system camera and projectorunit 121 is attached to the end-effector 122 of the robot manipulator123 via an extension structure 124 which allows it to be positioned at afar enough distance from the treatment surface area 125 to provide itwith a wide enough field of view to allow a relatively large field ofview to accommodate larger treatment areas. This embodiment of thepresent invention preferably would also use a commercially availableEr-YAG laser head system 126 (such as the Profile Surgical Laser systemfrom Sciton, Inc., Palo Alto, Calif.), which is similarly attacheddirectly to the end-effector 122 of the same robot manipulator arm 123.This embodiment would also tolerate a relatively large movement of thepatient 127 during the treatment.

A smoke evacuation vacuum head 129 is provided to evacuate the generatedsmoke and debris resulting from the debridement or other operations.Such smoke evacuation systems are well known in the art and may use aircirculation to increase the efficiency of the evacuation system. Theevacuated flow is usually filtered using appropriate filtering systemsthat are routinely cleaned and their filters replaced when suchdisposable filters are utilized. The smoke evacuation head 129 can beattached to the end-effector 122 of the robot arm 123, directly orthrough the extension structure 124. The advantage of having the smokeevacuation vacuum head 129 in a fixed position relative to the laserhead 126 is that it would then almost always be in a proper position toevacuate the generated smoke. This is compared to the positioning of thesmoke evacuation vacuum head 111 in the embodiment of FIGS. 1 and 2, inwhich it is fixed to the bed 113, and therefore it may have to berepositioned during the treatment for proper evacuation of the generatedsmoke and debris.

This embodiment of the present invention has the followingconfiguration, characteristics, advantages and shortcomings relative tothe other embodiments disclosed herein:

-   -   1. An advantage of the present embodiment 120 over the previous        embodiment 100 is that in this system configuration, the laser        head 126 position is fixed relative to the position of the 3D        vision system 121, i.e., its position is fixed in the “global”        coordinate system of the 3D vision system 121 (and vise versa),        thereby the need for continuous laser head 126 position and        orientation calibration relative to a (global) coordinate system        of the 3D vision system 121 (or vise versa) is eliminated. It is        noted that a “global” coordinate system may alternatively be        fixed to the laser system 126, or the robot manipulator arm 123,        to the bed 128 or patient 127, and in fact may be arbitrarily        positioned. However, since the 3D vision system 121 provides the        means of all surface and other positioning and orientation        measurements, it is preferred to have a global coordinate system        be fixed in the said 3D vision system 121 and all position and        orientation, surface, curve, point, etc., measurements be        described in this coordinate system. This would in general        reduce overall measurement and calculation errors, complexity        and increase computational speed. In addition, the position and        orientation of the laser head 126 and thereby the laser spot        over the treatment surface is more accurately known at all        times. The complexity of the system software is also reduced,        while the system safety is enhanced. The position of the laser        head 126 in the 3D vision system 121 coordinate system may still        be checked frequently to test the proper operation of the laser        scanning head 126 and its accidental misalignment.    -   2. The main shortcoming of the system configuration of this        embodiment 120 as compared with that of the previous embodiment        100 is that the laser head 126 may at times block the field of        view of the 3D vision system 121 over the entire treatment area        125. This is not in general an issue since the immediate areas,        most of the circumscribed curves 130, tick marks 131, markers        132, etc., are always in the field of view of the vision system,        and the entire treatment area 125 is readily scanned prior to        the treatment process. The entire treatment area 125 may also be        updated by occasional movement of the end-effector 122 of the        robot arm 123 above the entire treatment area 125 followed by        resumption of the treatment process.

The end-effector extension structure 124 of the present embodiment ofthe automated Er-YAG laser debridement system is preferably providedwith several attachment points (not shown) for the 3D vision systemcamera and projector unit 121, providing several choices for thepositioning of the 3D vision system 121 relative to the laser head 126.This simple capability would allow this embodiment of the presentinvention to be used for a wide range of treatment area 125 sizes,including very small treatment areas, for which the 3D vision system 121will be positioned at a minimum distance to provide maximum surfacedetail and laser scanning 126 precision, preferably placing it up and bythe laser head 126 itself.

Yet another embodiment is shown in the schematics of FIG. 5, a close-upof which is shown in FIG. 6. In this embodiment 140 of the automatedEr-YAG laser debridement system, a custom designed Er-YAG laser scanninghead with integrated vision system camera and projector 141 is employed.

It is noted that in the schematics of FIG. 6, the above three componentsof this integrated unit, i.e., the laser head 143 and the 3D visionsystem camera and projector 142, are shown individually as mounted on asingle base 144 (FIG. 5) for the sake of illustration clarity. The laserhead 143 uses a commercially available Er-YAG laser source and its laserbeam is delivered via a fiber optic cable (not shown). A commerciallyavailable motorized mirror based scanner or the like (not shown) can beused to scan the laser beam 145 two-dimensionally with the patternsynthesized by the system control computer. Such motorized mirror basedscanners that could be used include those commercially available fromBlue Hill Optical Technologies, located in Norwood, Mass. or NutfieldTechnology, Windham, N.H.

The laser head and vision system camera and projector unit assembly 141,hereinafter collectively called as the “Integrated Laser Scanning andReal-Time Vision System” or ILSRTV system, is attached as can be seen inFIGS. 5 and 6 to a gantry type frame 147 that is positioned above thepatient 146 over the area to be treated 148.

In one embodiment of this invention, the frame 147 and the base rail (orthe like) 148, which is fixed to the treatment bed 149, form a gantrytype of robotic manipulation system. The ILSRTV system 141 is thenmounted on a guide fixed to the frame 147 (not shown), which would allowit to be positioned over a range of positions shown as dashed line 150that can arbitrarily position the laser head and the ILSRTV system 141along the desired length of the patient 146 body.

Alternatively, the ILSRTV system 141, FIG. 5, is moved over its range ofpositions 150 by a motor controlled by the (robotic) system control.Alternatively, the ILSRTV system 141 is moved manually along its rangeof positions 150 and preferably locked in position. Alternatively, whenthe treatment area 148 is either relatively small or the patient 146 canbe moved after treatment of a portion of the body surface to be treated,the ILSRTV system 141 may be fixed to the gantry frame 147.

In FIGS. 5 and 6, the ILSRTV system 141 is shown to consist of a singlelaser head 143. Alternatively, more than one such laser heads 143 may beused (preferably with one source for the one or more lasers used) tocover significantly larger treatment surface areas 148 than is possiblewith a single laser head 143. The one or more laser sources arepreferably routed selectively to the desired laser head 143 using wellknown optical switching circuitry. It is noted that with severalscanning heads and a single laser source (for each laser type used) thesystem could cover very large treatment surface areas (or alternativelyreduce the maximum required ILSRTV system distance to the treatmentarea). When very large treatment areas are to be treated with multiplelaser heads 143, then more than one set of 3D vision system camera andprojector 142 may be required to cover the entire treatment areas withthe desired precision.

It is appreciated by those familiar with the art that even though anarc-type and two rail gantry system is shown in the schematics of theembodiment 140, any other gantry type (such as one rail type) or anyother type of such robotic system may be used instead. This embodimentcan be suitable for hospitals or other similar settings due to the totalsize and weight of the system. The gantry system can be integrated intothe structure of the bed.

The primary advantage of the embodiment 140 over the embodiments 100 and120 is that the geometric relationship of the 3D vision system cameraand projector system 142 with the laser scanner head 143 is fixed in theILSRTV system and pre-calibrated. Once the treatment area 148 and its 3Dgeometry are determined, a simple algorithm is used to plan the scanningpath of the laser beam 145. During the treatment process, the scanningpath of the laser beam 145 is constantly corrected to account forpotential body motions of the subject as previously described.

This embodiment has the following configuration, characteristics,advantages and shortcomings relative to the other embodiments:

-   -   1. The laser head 143 is preferably fabricated by integrating        available Er-YAG and other laser sources when necessary and a        visual spotting laser source and a commercially available        galvanometer type scanner. The scanning pattern can then be        readily and automatically synthesized by the system control        computer. Similar computer controlled scanning heads are        commonly used in a wide range of applications and the related        art is well known.    -   2. Once the treatment area 148 and its 3D geometry is mapped by        the 3D vision system and the physician has interactively        indicated the various regions to be scanned and the        corresponding laser scanning parameters, a simple algorithm is        used to plan and synthesize the scanning path of the laser beam        145 over the indicated treatment area(s) 148.    -   3. During the treatment process, the scanning path of the laser        beam 145 is constantly corrected to account for potential        movement of the patient 146 body. High-speed correction is        possible due to the near real-time nature of the 3D vision        system 142.    -   4. Since the laser head 143 is positioned farther away from the        treatment surface area 148 as is the case for the previous        embodiments 100 and 120, in which the laser heads 108 and 126        are designed for hand operation, relatively large surface areas        148 can be treated from a single positioning of the laser head.        For example, it should be possible to treat an area with a        diameter of over 10-12 inches or more from a distance of around        10-12 inches. The possible range of ILSRTV system 141 distances        to the treatment areas 148 and the maximum surface area that can        be covered within an acceptable deviation of the laser beam 145        from the direction of normal to the treatment surface 148 are        described in more detail later in this disclosure.    -   5. For systems that are to cover very large areas of the patient        body, for example the entire length of the patient body, the        robotic gantry system (147 traveling along the rail(s) 148) will        require only two degrees-of-freedom; one corresponding to the        motion of the gantry arch 147 along the length of the bed 149        over the rail(s) 148, and the second corresponding to the        positioning of the base 144 of the ILSRTV system 141 along the        gantry arch (as shown in dotted line in the schematic of FIG.        5).

As described above, in one alternative of the embodiment shownschematically in FIGS. 5 and 6, the longitudinal positioning of thegantry arch 147 (for example along the guide 148 or at discretelongitudinal positioning) is manual. The arch can be locked at each ofits desired longitudinal positioning before the treatment process isinitiated. The positioning of the base 144 of the ILSRTV 141 over thegantry arch 147 can be automated. Alternatively, a permanent ortemporary guide for the longitudinal motion of the arch 147 may not benecessary, particularly if the patient 146 is restrained or is notconscious. For relatively small movements, due to the near real-timeoperation of the present 3D vision system, the feedback loop of thelaser beam control system is capable of ensuring proper scanning of theindicated treatment areas 148. For increased safety, a second visionsystem camera may be used to monitor the error between the actual andthe programmed positioning of the laser spot over the treatment area andturn the power to the treatment laser(s) off in case the error is morethan a specified threshold. Additional safety can be provided via atri-axial accelerometer (or another similar motion sensory device) basedsafety switch, which would shut the laser power off when a suddenmovement of the ILSRTV system 14 is detected. Such a capability wouldprevent accidental exposure if some object or person collides with thearch 147 and/or the ILSRTV system 141 or their wiring, which couldresult in a sudden movement of the laser beam before the 3D visionsystem 142 (or aforementioned additional vision camera) has a chance todetect it. Such tri-axial accelerometers can be readily integrated intoany of the embodiments disclosed herein.

A second alternative of the embodiment shown schematically in FIGS. 5and 6 is identical to the above first alternative with the exceptionthat the adjustment of the position of the base 144 of the ILSRTV system141 over the gantry arch 147 is performed manually, using any one of thewell known means, such as guide and carriage type. This manualadjustment capability may, however, be motorized. Means of locking basedto the gantry arch can be provided to minimize the possibility that theILSRTV system 141 is accidentally moved during the treatment process dueto an object or person striking it or for any other reasons. The systemis preferably equipped with the aforementioned sudden motion detectioncapability sing accelerometers or other similar motion detectionsensors.

This alternative embodiment may be fabricated with a very lightweightarched central rail, supported by a collapsible side support “legs” thatcan be quickly deployed and locked in place, and which could becollapsed to fit into a relatively small carrying case. The entiresystem would then be very portable, while being capable of covering thespecified treatment area at each setting.

In yet another alternative of the embodiment shown schematically inFIGS. 5 and 6, the system is identical to the above first alternativewith the exception that the base 144 of the ILSRTV system 141 isattached directly to a manually adjustable floor stand, preferably onethat is provided with locking wheels. The system can then be readilymoved to the desired position relative to the patient and locked inplace. The floor stand is preferably provided with an articulating armto allow proper positioning of the ILSRTV system 141 over the treatmentarea 148. Such an embodiment is described in detail below. It is notedthat the described embodiment is particularly suitable for debridementof chemical and thermal burns.

It is, however, appreciated by those familiar with the art that numerousother similar alternatives are possible for the embodiments 100, 120 and140 shown in the schematics of FIGS. 1-6 and their aforementionedalternative embodiments. These obviously include those obtained bycombining various features of one or more of these embodiments. Inaddition, and generally at the cost of increasing system complexity andcost, more than one scanning head (preferably using a single lasersource) and/or 3D vision systems could be employed to significantlyincrease the visual coverage and the treatment area coverage withminimal or no movement of the laser head and/or the 3D vision system.Additional cameras (and/or 3D vision systems) may also be used toprovide added means for very rapid sensing of the laser beam spotposition error during the treatment and/or to provide an overall (macroand generally coarse and less precise) vision of the patient and thetreatment areas, the laser head, the 3D vision system, the attendingpersonnel, etc., for reasons such as overall safety.

Still yet another embodiment 200 of the present invention is shown inFIG. 7. FIG. 8 shows the general positioning of the embodiment 200during the treatment of a patient 201 laying over the bed 202. Thesystem 200 is designed to be self-contained, requiring only electricalpower for operation. The system 200, with its articulating arm stowedover the base cabinet, can be readily stored or moved to a side until itis needed again. The setup of the system 200 will generally proceed asfollows:

-   -   1. Wheel the system 200 into approximate position and lock        wheels 203.    -   2. Grasp treatment head handle(s) 204 and depress button (not        shown) to unlock joints 205 of articulating arm 206. Such        articulating arms are well known in the art.    -   3. Position treatment head 207 such that the bottom periphery of        the laser shield 208 is close to the patient 201 and envelopes        the desired treatment area.    -   4. Position the LCD touch screen 209 in a convenient location        such that the user may interface with the patient 201 and the        computer simultaneously.

The base cabinet 210 for the laser debridement system 200 serves threemain functions. Firstly, equipped with wheels 203, preferably of lockingcaster type, the cabinet 210 provides for easy transport of the system200 and for secure placement near the bed 202 with the patient 201.Secondly, the cabinet 210 is massive and acts as a counterbalance toprevent the system 200 from tipping over when the articulating treatmentarm 206 is extended over the patient 201. Finally, the cabinet 210houses many of the larger, heavier components of the system 200. Placingthese components within the cabinet 210 helps to increase the stabilityof the system 200 and also isolates the components from the operatingtheatre and vice-versa. The main components contained within the cabinet210 are:

-   -   1. A computer, preferably of PC type, which controls the 3D        vision and laser scanning systems.    -   2. The laser sources and their power sources and cooling systems        if any (described later in this disclosure).    -   3. The vacuum generator for the smoke evacuation system        (described later in this disclosure), preferably equipped with a        HEPA filtration system.

The articulating arm 206 of the laser debridement system 200 servesthree main functions. Primarily, the arm provides a means by which thetreatment head 207 may be positioned over a patient 201 laying on astandard operating table 202. The articulating arm 206 is preferablyprovided with automatic-locking (preferably rotary) joints,counterbalance springs (not shown), and a release button located on thehandle 204 of the treatment head 207. The articulating arm 206 ispreferably provided with at least four rotary joints to allow thepositioning of the treatment head in an arbitrary position over thetreatment area. Such articulating arms 206 and their aforementionedcomponents are well known in the art.

When the handle 204 of the treatment head 207 is grasped and the releasebutton depressed, the joints 205 of the articulating arm 206 areunlocked and the counterbalance springs provide stability while theoperator positions the treatment head 207 over the treatment area of thepatient 201. Upon release of the button and handle, the joints 205 ofthe articulating arm 206 lock the articulating arm in positionautomatically. The (rotary) joints are provided with bellows 211 toprevent contaminants in the joints from entering the operating theaterand vice-versa, and to provide a smooth wash-down surface for regularcleaning and sterilization. One of the joints 205 is preferably a singleparallel-axis rotary joint which attaches the articulating arm 206 tothe base cabinet 210 may be outfitted with an appropriate lip seal toprovide the same functions as the bellows on the other joints 205.

The secondary function of the articulating arm is to provide a conduitthrough which the 3D vision system cables, laser fiber optic cables, andthe vacuum tubing for the smoke evacuator can be routed from the basecabinet 210 to the treatment head 207. Like the bellows 211, this cableand tube routing is to provide a smooth, continuous surface for regularcleaning of the articulating arm. Finally, the articulating arm may alsobe used to support the (preferably swiveling cantilever) mount for theLCD touch screen 209. This type of screen and mounting is chosen tooffer the operator a slender interface with the computer which can bepositioned at any convenient orientation and operated with a stylus toavoid touching the screen directly.

The details of a typical treatment head 207 design with and without thelaser shield 208 is shown in FIGS. 9 and 10, respectively. The treatmenthead 207 is attached to the end of the articulating arm 206 as shown inFIGS. 7-10. The treatment head 207 consists of the aforementioned ILSRTVsystem 212, consisting of the 3D vision camera 213 and projector 214,and laser scanning housing 215; two handles 204; a laser shield 208,opaque to the wavelengths of the treatment lasers and otherwise visuallytransparent; a protective (top) glass plate 216 which is preferablyfabricated or coated to be opaque to the wavelengths of the treatmentlasers and otherwise visually transparent; and smoke evacuation manifold217 with evacuation openings 218 and ducts 219. Also shown is theconical workspace 220 of the laser scanning head 214. A conicalworkspace with a cone angle of 20-40 degrees is generally preferred.Clearly, with the attachment of different shield assemblies, a pluralityof treatment area sizes and shapes can be realized.

As it is shown in FIG. 10, the ILSRTV system 212 housing contains the 3Dvision camera 213 and projector 214 and laser scanning housing 215, andserves as a thoroughfare for routing the smoke evacuation tubing 219through the articulating arm 206, back to the HEPA filter (not shown) inthe base cabinet 210 (FIG. 10). The protective glass plate 216 isprovided to protect the ILSRTV system 212 from contamination from anysmoke or other debris which is not immediately collected by the smokeevacuation system.

The laser shield 208 prevents any errant directions or reflections ofthe treatment laser(s) from exiting the treatment head 207. Whenpositioned as close as practical to the patient 208, FIG. 8, anyunacceptable gaps in the laser shield 208 may be blocked with smallersheets of protective laser-blocking material (preferably movablepanels—not shown). The shield also provides a chamber to contain smokeor other debris which is not immediately collected by the smokeevacuation system, and serves as a hard-guard to prevent the operator orother bystanders from accidentally crossing the path of the (mostlyinvisible) treatment laser beams during treatment.

The laser beam is preferably delivered via a fiber optic cable (notshown) to the scanning head as it is commonly done in the art. For laserbeam scanning, a galvanometer based scanner is preferably used aspreviously indicated, which allows for the laser beam to be scannedtwo-dimensionally in any arbitrary pattern. This capability is importantbecause burn areas are most likely in irregular shapes. Being able toscan in any arbitrary pattern prevents healthy tissues from beingremoved.

The 3D vision system projector 213 and (CCD) camera 214 are connected tothe system PC (not shown) but located in the base cabinet 210. Aspreviously described for previous embodiments of the present invention,the 3D vision system automatically locates the circumscribing curve andits position tick marks and markers (see for example FIG. 4) anddetermines the coordinates of the treatment area for laser scanningDuring the treatment process, the circumscribing curve and associatedposition tick marks and markers (if any) are constantly monitored by thevision system for signs of significant body movement. When significantbody movement is detected, the coordinates of the laser scan area areupdated to compensate for the body movement and the process continues.The position of the laser spot on the surface of the treatment area issimilarly measured and compared to its expected position and used tocorrect its positioning and if the error exceeds a set threshold, thenpower to the treatment laser is shut off and a warning message is sentto the control monitor 209, and preferably a warning light is lit and/oran audio warning sound is activated.

To ensure accurate scanning of the laser beam based on the coordinateinformation provided by the 3D vision system, the geometric relationshipbetween the laser scanner and the 3D vision system needs to beaccurately determined. This is accomplished through calibration, whichis aimed at determining the equation of the laser beam as a line in thecoordinate system of the vision system. However, since this geometricrelationship is fixed, once the calibration is done, the system willmaintain its accuracy for as long as this geometric relationship ismaintained. In such systems, system calibration is periodically checkedand recalibration is made whenever it is determined to be required.

As discussed above, the need to manually mark the burnt area in need ofdebridement can be eliminated by the use of a recognition system whichcan differentiate the burnt area from healthy tissue. Recognitionsystems for recognizing burnt tissue are known in the art.

One of the largest uses for lasers in dermatology is the removal oftattoos. The systems disclosed herein can operate for use in removingtattoos. The laser heads can have various lasers for use with specificcolors of the tattoo. Besides the marking and tic marks disclosed above,the system can use a recognition system to detect the colors in thetattoo and selectively and automatically remove the tattoo by destroyingtattoo pigment without causing much damage to the surrounding skin. Thealtered pigment is then removed from the skin by scavenging white bloodcells, tissue macrophages. The choice of laser depends on the color,depth and chemical nature of the tattoo ink. The present system allowsfor automatic switching between different lasers depending on the colorpigment detected.

Lasers have also become very popular to remove excessive hair. Lasertreatments remove dark hair quickly and it may take 3 to 6 months beforeregrowth is evident. Such laser treatments are less painful and muchquicker than electrolysis. In current systems, a physician or highlytrained technician tediously identifies each of the unwanted hairs andmanually directs a laser to the hair. Alternatively, the techniciandirects the laser to an entire surface, regardless of whether hairfollicles are present. Several treatment cycles are required with thespacing between treatments dependent on the body area being treated. Thedark hair (usually nubs that are recently shaved) can be easilyrecognized with a computer recognition system and targeted by theautomated laser system. The disclosed automated system can eliminate theneed for a physician or highly trained technician and greatly speed upthe process.

Pulsed CO₂ and erbium:YAG lasers have been used successfully in reducingand removing facial wrinkles, acne scars and sun-damaged skin. Typicallya 50% improvement is found in patients receiving CO₂ laser treatment.The disclosed automated system can greatly speed up the process,particularly by the provision of recognition algorithms. Again, arecognition system can be used to recognize the facial wrinkles, acnescars and sun-damaged skin to eliminate the need to manually mark thesame.

There are also some skin scaling and sclerosis conditions, which wouldneed entire body treatment (in some cases they use the light scanning toactivate the drug on the skin surface). The systems disclosed herein canprovide a whole body treatment that would generate a real-time 3D imageof the body surface and then scan all the affected areas as indicated bythe physician. Alternatively, the affected areas can be automaticallylocated by a vision system. In either case, the real-time surfacemeasurement information is used by a controller to control the laserscanning to treat the affected areas.

For the last decade, lasers have been used in the fight against agingskin. Laser resurfacing is a very controlled burning procedure duringwhich a laser vaporizes superficial layers of facial skin, removing notonly wrinkles and lines caused by sun damage and facial expressions, butalso acne scars, some folds and creases around the nose and mouth, andeven precancerous and benign superficial growths. In a sense, the laserprocedure creates a fresh surface over which new skin can grow. Collagenis a key fibrous protein in the skin's connective tissue, and it helpsgive the skin its texture. Natural aging and such factors as sun damageand smoking help break down the collagen layer so that the skin's oncesmooth surface develops wrinkles New, more youthful collagen actuallyforms after laser treatment. The disclosed automated laser debridementsystem can readily map the face of the patient and recognize andeliminate areas where laser surfacing is not needed, for example, abovethe hairline, the lips, the eyes and eye lids, eyebrows and other facialhair areas. Furthermore, other features, such as around the lips andnose, can be automatically identified. The identified portions of thepatients face, other than the excluded areas can then be laserresurfaced automatically without the need for constant monitoring by anattending physician or medical technician.

However, perhaps the largest group of patients who can potentiallybenefit from cosmetic laser procedures are those with scars resultingfrom surgery. In the U.S. alone, the ongoing surgical caseload producesmore than 50 million incision sites annually that can benefit from earlyintervention with laser treatment (a C-beam pulsed dye laser has beenfound to be effective on scar tissue). This is a larger patientpopulation than any other group in the aesthetic laser field. Itincludes all plastic surgery (particularly facelifts), abdominal,breast, Cesarean sections, sternotomies, small telltale scars fromliposuction and other less invasive procedures, and others. The novelautomated laser debridement system disclosed above can recognize scartissue, such as by the differences in certain image characteristics ofthe scar tissue as compared to healthy tissue and control the robot armto direct the laser only at such scar tissue.

While there has been shown and described what is considered to bepreferred embodiments of the invention, it will, of course, beunderstood that various modifications and changes in form or detailcould readily be made without departing from the spirit of theinvention. It is therefore intended that the invention be not limited tothe exact forms described and illustrated, but should be constructed tocover all modifications that may fall within the scope of the appendedclaims.

1. A method for automated treatment of an area of skin of a patient withlaser energy, the method comprising: identifying the area to be treatedwith the laser; modeling the identified area of the skin to be treated;and controlling the laser to direct laser energy to within the modeledarea of the skin.
 2. The method of claim 1, further comprisingprojecting one or more reference markers on the skin.
 3. The method ofclaim 1, further comprising evacuating smoke resulting from theinteraction of the laser energy with the skin of the area.
 4. The methodof claim 1, wherein the identifying comprises outlining the area to betreated such that the modeling models the area within the outline. 5.The method of claim 1, wherein the identifying comprises recognizing thearea to be treated based on a unique characteristic of the area whichdiffers from normal skin tissue.
 6. The method of claim 1, furthercomprising repeating the identifying and modeling steps to account forany movement of the patient.
 7. The method of claim 1, wherein theidentifying identifies burned skin.
 8. The method of claim 1, whereinthe identifying identifies a tattoo.
 9. The method of claim 1, whereinthe identifying identifies facial features.
 10. The method of claim 1,wherein the identifying identifies scar tissue.
 11. The method of claim1, wherein the identifying identifies hairs on a surface of the skin.12. The method of claim 1, wherein the identifying identifies one ormore of acne scars, skin folds, skin creases, pre-cancerous and benigngrowths on the skin.